1
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Kim J, Moon S, Romo TD, Yang Y, Bae E, Phillips GN. Conformational dynamics of adenylate kinase in crystals. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:014702. [PMID: 38389978 PMCID: PMC10883716 DOI: 10.1063/4.0000205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 12/14/2023] [Indexed: 02/24/2024]
Abstract
Adenylate kinase is a ubiquitous enzyme in living systems and undergoes dramatic conformational changes during its catalytic cycle. For these reasons, it is widely studied by genetic, biochemical, and biophysical methods, both experimental and theoretical. We have determined the basic crystal structures of three differently liganded states of adenylate kinase from Methanotorrus igneus, a hyperthermophilic organism whose adenylate kinase is a homotrimeric oligomer. The multiple copies of each protomer in the asymmetric unit of the crystal provide a unique opportunity to study the variation in the structure and were further analyzed using advanced crystallographic refinement methods and analysis tools to reveal conformational heterogeneity and, thus, implied dynamic behaviors in the catalytic cycle.
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Affiliation(s)
- Junhyung Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea
| | - Sojin Moon
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea
| | - Tod D Romo
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Yifei Yang
- Departments of BioSciences, Rice University, Houston, Texas 77005, USA
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2
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Shukla VK, Heller GT, Hansen DF. Biomolecular NMR spectroscopy in the era of artificial intelligence. Structure 2023; 31:1360-1374. [PMID: 37848030 DOI: 10.1016/j.str.2023.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/15/2023] [Accepted: 09/21/2023] [Indexed: 10/19/2023]
Abstract
Biomolecular nuclear magnetic resonance (NMR) spectroscopy and artificial intelligence (AI) have a burgeoning synergy. Deep learning-based structural predictors have forever changed structural biology, yet these tools currently face limitations in accurately characterizing protein dynamics, allostery, and conformational heterogeneity. We begin by highlighting the unique abilities of biomolecular NMR spectroscopy to complement AI-based structural predictions toward addressing these knowledge gaps. We then highlight the direct integration of deep learning approaches into biomolecular NMR methods. AI-based tools can dramatically improve the acquisition and analysis of NMR spectra, enhancing the accuracy and reliability of NMR measurements, thus streamlining experimental processes. Additionally, deep learning enables the development of novel types of NMR experiments that were previously unattainable, expanding the scope and potential of biomolecular NMR spectroscopy. Ultimately, a combination of AI and NMR promises to further revolutionize structural biology on several levels, advance our understanding of complex biomolecular systems, and accelerate drug discovery efforts.
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Affiliation(s)
- Vaibhav Kumar Shukla
- Department of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Gabriella T Heller
- Department of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, UK.
| | - D Flemming Hansen
- Department of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, UK.
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3
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Zuiderweg ER, Case DA. New experimental evidence for pervasive dynamics in proteins. Protein Sci 2023; 32:e4630. [PMID: 36949673 PMCID: PMC10108438 DOI: 10.1002/pro.4630] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 03/24/2023]
Abstract
There is ample computational, but only sparse experimental data suggesting that pico-ns motions with 1 Å amplitude are pervasive in proteins in solution. Such motions, if present in reality, must deeply affect protein function and protein entropy. Several NMR relaxation experiments have provided insights into motions of proteins in solution, but they primarily report on azimuthal angle variations of vectors of covalently-linked atoms. As such, these measurements are not sensitive to distance fluctuations, and cannot but under-represent the dynamical properties of proteins. Here we analyze a novel NMR relaxation experiment to measure amide proton transverse relaxation rates in uniformly 15 N labeled proteins, and present results for protein domain GB1 at 283 and 303 K. These relaxation rates depend on fluctuations of dipolar interactions between 1 HN and many nearby protons on both the backbone and sidechains. Importantly, they also report on fluctuations in the distances between these protons. We obtained a large mismatch between rates computed from the crystal structure of GB1 and the experimental rates. But when the relaxation rates were calculated from a 200 ns molecular dynamics trajectory using a novel program suite, we obtained a substantial improvement in the correspondence of experimental and theoretical rates. As such, this work provides novel experimental evidence of widespread motions in proteins. Since the improvements are substantial, but not sufficient, this approach may also present a new benchmark to help improve the theoretical forcefields underlying the molecular dynamics calculations.
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Affiliation(s)
- Erik R.P. Zuiderweg
- Radboud UniversityInstitute for Molecules and MaterialsNijmegenXZ6525The Netherlands
- University of Michigan Medical School, Department of Biological ChemistryAnn ArborMichigan41109USA
| | - David A. Case
- Rutgers University, Department of Chemistry & Chemical Biology PiscatawayNew Jersey08854USA
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4
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Abstract
This Perspective presents a review of our work and that of others in the highly controversial topic of the coupling of protein dynamics to reaction in enzymes. We have been involved in studying this topic for many years. Thus, this perspective will naturally present our own views, but it also is designed to present an overview of the variety of viewpoints of this topic, both experimental and theoretical. This is obviously a large and contentious topic.
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Affiliation(s)
- Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
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5
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Pinkston J, Jo J, Olsen KJ, Comer D, Glaittli CA, Loria JP, Johnson SJ, Hengge AC. Significant Loop Motions in the SsoPTP Protein Tyrosine Phosphatase Allow for Dual General Acid Functionality. Biochemistry 2021; 60:2888-2901. [PMID: 34496202 DOI: 10.1021/acs.biochem.1c00365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Conformational dynamics are important factors in the function of enzymes, including protein tyrosine phosphatases (PTPs). Crystal structures of PTPs first revealed the motion of a protein loop bearing a conserved catalytic aspartic acid, and subsequent nuclear magnetic resonance and computational analyses have shown the presence of motions, involved in catalysis and allostery, within and beyond the active site. The tyrosine phosphatase from the thermophilic and acidophilic Sulfolobus solfataricus (SsoPTP) displays motions of its acid loop together with dynamics of its phosphoryl-binding P-loop and the Q-loop, the first instance of such motions in a PTP. All three loops share the same exchange rate, implying their motions are coupled. Further evidence of conformational flexibility comes from mutagenesis, kinetics, and isotope effect data showing that E40 can function as an alternate general acid to protonate the leaving group when the conserved acid, D69, is mutated to asparagine. SsoPTP is not the first PTP to exhibit an alternate general acid (after VHZ and TkPTP), but E40 does not correspond to the sequence or structural location of the alternate general acids in those precedents. A high-resolution X-ray structure with the transition state analogue vanadate clarifies the role of the active site arginine R102, which varied in structures of substrates bound to a catalytically inactive mutant. The coordinated motions of all three functional loops in SsoPTP, together with the function of an alternate general acid, suggest that catalytically competent conformations are present in solution that have not yet been observed in crystal structures.
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Affiliation(s)
- Justin Pinkston
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
| | - Jihye Jo
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Keith J Olsen
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
| | - Drake Comer
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
| | - Charsti A Glaittli
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
| | - J Patrick Loria
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06520, United States
| | - Sean J Johnson
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
| | - Alvan C Hengge
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
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6
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Abstract
This review examines low-frequency vibrational modes of proteins and their coupling to enzyme catalytic sites. That protein motions are critical to enzyme function is clear, but the kinds of motions present in proteins and how they are involved in function remain unclear. Several models of enzyme-catalyzed reaction suggest that protein dynamics may be involved in the chemical step of the catalyzed reaction, but the evidence in support of such models is indirect. Spectroscopic studies of low-frequency protein vibrations consistently show that there are underdamped modes of the protein with frequencies in the tens of wavenumbers where overdamped behavior would be expected. Recent studies even show that such underdamped vibrations modulate enzyme active sites. These observations suggest that increasingly sophisticated spectroscopic methods will be able to unravel the link between low-frequency protein vibrations and enzyme function.
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7
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Fu X, Chang Z. Biogenesis, quality control, and structural dynamics of proteins as explored in living cells via site-directed photocrosslinking. Protein Sci 2019; 28:1194-1209. [PMID: 31002747 DOI: 10.1002/pro.3627] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/16/2019] [Indexed: 02/06/2023]
Abstract
Protein biogenesis and quality control are essential to maintaining a functional pool of proteins and involve numerous protein factors that dynamically and transiently interact with each other and with the substrate proteins in living cells. Conventional methods are hardly effective for studying dynamic, transient, and weak protein-protein interactions that occur in cells. Herein, we review how the site-directed photocrosslinking approach, which relies on the genetic incorporation of a photoreactive unnatural amino acid into a protein of interest at selected individual amino acid residue positions and the covalent trapping of the interacting proteins upon ultraviolent irradiation, has become a highly efficient way to explore the aspects of protein contacts in living cells. For example, in the past decade, this approach has allowed the profiling of the in vivo substrate proteins of chaperones or proteases under both physiologically optimal and stressful (e.g., acidic) conditions, mapping residues located at protein interfaces, identifying new protein factors involved in the biogenesis of membrane proteins, trapping transiently formed protein complexes, and snapshotting different structural states of a protein. We anticipate that the site-directed photocrosslinking approach will play a fundamental role in dissecting the detailed mechanisms of protein biogenesis, quality control, and dynamics in the future.
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Affiliation(s)
- Xinmiao Fu
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, 350117, China
| | - Zengyi Chang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Center for Protein Science, Beijing, 100871, China
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8
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Shen YH, Tsai ST, Liew CY, Ni CK. Mass spectrometry-based identification of carbohydrate anomeric configuration to determine the mechanism of glycoside hydrolases. Carbohydr Res 2019; 476:53-59. [DOI: 10.1016/j.carres.2019.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 03/10/2019] [Accepted: 03/11/2019] [Indexed: 10/27/2022]
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9
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Subunit interactions as mediated by “non-interface” residues in living cells for multiple homo-oligomeric proteins. Biochem Biophys Res Commun 2019; 512:100-105. [DOI: 10.1016/j.bbrc.2019.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 03/01/2019] [Indexed: 11/22/2022]
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10
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Roca M, Ruiz-Pernía JJ, Castillo R, Oliva M, Moliner V. Temperature dependence of dynamic, tunnelling and kinetic isotope effects in formate dehydrogenase. Phys Chem Chem Phys 2018; 20:25722-25737. [PMID: 30280169 DOI: 10.1039/c8cp04244f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The origin of the catalytic power of enzymes has been a question of debate for a long time. In this regard, the possible contribution of protein dynamics in enzymatic catalysis has become one of the most controversial topics. In the present work, the hydride transfer step in the formate dehydrogenase (FDH EC 1.2.1.2) enzyme is studied by means of molecular dynamic (MD) simulations with quantum mechanics/molecular mechanics (QM/MM) potentials in order to explore any correlation between dynamics, tunnelling effects and the rate constant. The temperature dependence of the kinetic isotope effects (KIEs), which is one of the few tests that can be studied by experiments and simulations to shed light on this debate, has been computed and the results have been compared with previous experimental data. The classical mechanical free energy barrier and the number of recrossing trajectories seem to be temperature-independent while the quantum vibrational corrections and the tunnelling effects are slightly temperature-dependent over the interval of 5-45 °C. The computed primary KIEs are in very good agreement with previous experimental data, being almost temperature-independent within the standard deviations. The modest dependence on the temperature is due to just the quantum vibrational correction contribution. These results, together with the analysis of the evolution of the collective variables such as the electrostatic potential or the electric field created by the protein on the key atoms involved in the reaction, confirm that while the protein is well preorganised, some changes take place along the reaction that favour the hydride transfer and the product release. Coordinates defining these movements are, in fact, part of the real reaction coordinate.
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Affiliation(s)
- Maite Roca
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
| | | | - Raquel Castillo
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
| | - Mónica Oliva
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
| | - Vicent Moliner
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
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11
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Saavedra JM, Azócar MA, Rodríguez V, Ramírez-Sarmiento CA, Andrews BA, Asenjo JA, Parra LP. Relevance of Local Flexibility Near the Active Site for Enzymatic Catalysis: Biochemical Characterization and Engineering of Cellulase Cel5A FromBacillus agaradherans. Biotechnol J 2018; 13:e1700669. [DOI: 10.1002/biot.201700669] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/19/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Juan M. Saavedra
- Department of Chemical Engineering and Biotechnology; Centre for Biotechnology and Bioengineering (CeBiB); University of Chile; Santiago Chile
| | - Mauricio A. Azócar
- Department of Chemical Engineering and Biotechnology; Centre for Biotechnology and Bioengineering (CeBiB); University of Chile; Santiago Chile
| | - Vida Rodríguez
- Department of Chemical Engineering and Biotechnology; Centre for Biotechnology and Bioengineering (CeBiB); University of Chile; Santiago Chile
| | - César A. Ramírez-Sarmiento
- Institute for Biological and Medical Engineering; Schools of Engineering,; Medicine and Biological Sciences; Pontificia Universidad Católica de Chile; Avenida Vicuña Mackenna 4860 Santiago 7820436 Chile
| | - Barbara A. Andrews
- Department of Chemical Engineering and Biotechnology; Centre for Biotechnology and Bioengineering (CeBiB); University of Chile; Santiago Chile
| | - Juan A. Asenjo
- Department of Chemical Engineering and Biotechnology; Centre for Biotechnology and Bioengineering (CeBiB); University of Chile; Santiago Chile
| | - Loreto P. Parra
- Institute for Biological and Medical Engineering; Schools of Engineering,; Medicine and Biological Sciences; Pontificia Universidad Católica de Chile; Avenida Vicuña Mackenna 4860 Santiago 7820436 Chile
- Department of Chemical and Bioprocesses Engineering; School of Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
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12
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Biundo A, Ribitsch D, Guebitz GM. Surface engineering of polyester-degrading enzymes to improve efficiency and tune specificity. Appl Microbiol Biotechnol 2018; 102:3551-3559. [PMID: 29511846 DOI: 10.1007/s00253-018-8850-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/08/2018] [Accepted: 02/10/2018] [Indexed: 01/06/2023]
Abstract
Certain members of the carboxylesterase superfamily can act at the interface between water and water-insoluble substrates. However, nonnatural bulky polyesters usually are not efficiently hydrolyzed. In the recent years, the potential of enzyme engineering to improve hydrolysis of synthetic polyesters has been demonstrated. Regions on the enzyme surface have been modified by using site-directed mutagenesis in order to tune sorption processes through increased hydrophobicity of the enzyme surface. Such modifications can involve specific amino acid substitutions, addition of binding modules, or truncation of entire domains improving sorption properties and/or dynamics of the enzyme. In this review, we provide a comprehensive overview on different strategies developed in the recent years for enzyme surface engineering to improve the activity of polyester-hydrolyzing enzymes.
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Affiliation(s)
- Antonino Biundo
- Austrian Centre of Industrial Biotechnology (ACIB), Tulln an der Donau, Austria
| | - Doris Ribitsch
- Austrian Centre of Industrial Biotechnology (ACIB), Tulln an der Donau, Austria. .,Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences (BOKU), Tulln an der Donau, Austria.
| | - Georg M Guebitz
- Austrian Centre of Industrial Biotechnology (ACIB), Tulln an der Donau, Austria.,Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences (BOKU), Tulln an der Donau, Austria
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13
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The Exact Nuclear Overhauser Enhancement: Recent Advances. Molecules 2017; 22:molecules22071176. [PMID: 28708092 PMCID: PMC6152122 DOI: 10.3390/molecules22071176] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 07/10/2017] [Indexed: 02/04/2023] Open
Abstract
Although often depicted as rigid structures, proteins are highly dynamic systems, whose motions are essential to their functions. Despite this, it is difficult to investigate protein dynamics due to the rapid timescale at which they sample their conformational space, leading most NMR-determined structures to represent only an averaged snapshot of the dynamic picture. While NMR relaxation measurements can help to determine local dynamics, it is difficult to detect translational or concerted motion, and only recently have significant advances been made to make it possible to acquire a more holistic representation of the dynamics and structural landscapes of proteins. Here, we briefly revisit our most recent progress in the theory and use of exact nuclear Overhauser enhancements (eNOEs) for the calculation of structural ensembles that describe their conformational space. New developments are primarily targeted at increasing the number and improving the quality of extracted eNOE distance restraints, such that the multi-state structure calculation can be applied to proteins of higher molecular weights. We then review the implications of the exact NOE to the protein dynamics and function of cyclophilin A and the WW domain of Pin1, and finally discuss our current research and future directions.
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14
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Grimm LL, Weissbach S, Flügge F, Begemann N, Palcic MM, Peters T. Protein NMR Studies of Substrate Binding to Human Blood Group A and B Glycosyltransferases. Chembiochem 2017; 18:1260-1269. [PMID: 28256109 DOI: 10.1002/cbic.201700025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Indexed: 12/31/2022]
Abstract
Donor and acceptor substrate binding to human blood group A and B glycosyltransferases (GTA, GTB) has been studied by a variety of protein NMR experiments. Prior crystallographic studies had shown these enzymes to adopt an open conformation in the absence of substrates. Binding either of the donor substrate UDP-Gal or of UDP induces a semiclosed conformation. In the presence of both donor and acceptor substrates, the enzymes shift towards a closed conformation with ordering of an internal loop and the C-terminal residues, which then completely cover the donor-binding pocket. Chemical-shift titrations of uniformly 2 H,15 N-labeled GTA or GTB with UDP affected about 20 % of all crosspeaks in 1 H,15 N TROSY-HSQC spectra, reflecting substantial plasticity of the enzymes. On the other hand, it is this conformational flexibility that impedes NH backbone assignments. Chemical-shift-perturbation experiments with δ1-[13 C]methyl-Ile-labeled samples revealed two Ile residues-Ile123 at the bottom of the UDP binding pocket, and Ile192 as part of the internal loop-that were significantly disturbed upon stepwise addition of UDP and H-disaccharide, also revealing long-range perturbations. Finally, methyl TROSY-based relaxation dispersion experiments do not reveal micro- to millisecond timescale motions. Although this study reveals substantial conformational plasticity of GTA and GTB, the matter of how binding of substrates shifts the enzymes into catalytically competent states remains enigmatic.
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Affiliation(s)
- Lena Lisbeth Grimm
- Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | - Sophie Weissbach
- Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | - Friedemann Flügge
- Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | - Nora Begemann
- Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | - Monica M Palcic
- Department of Biochemistry and Microbiology, University of Victoria, P. O. Box 3800, STN CSC, Victoria, BC, V8W 3P6, Canada
| | - Thomas Peters
- Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562, Lübeck, Germany
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15
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Warshel A, Bora RP. Perspective: Defining and quantifying the role of dynamics in enzyme catalysis. J Chem Phys 2017; 144:180901. [PMID: 27179464 DOI: 10.1063/1.4947037] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Enzymes control chemical reactions that are key to life processes, and allow them to take place on the time scale needed for synchronization between the relevant reaction cycles. In addition to general interest in their biological roles, these proteins present a fundamental scientific puzzle, since the origin of their tremendous catalytic power is still unclear. While many different hypotheses have been put forward to rationalize this, one of the proposals that has become particularly popular in recent years is the idea that dynamical effects contribute to catalysis. Here, we present a critical review of the dynamical idea, considering all reasonable definitions of what does and does not qualify as a dynamical effect. We demonstrate that no dynamical effect (according to these definitions) has ever been experimentally shown to contribute to catalysis. Furthermore, the existence of non-negligible dynamical contributions to catalysis is not supported by consistent theoretical studies. Our review is aimed, in part, at readers with a background in chemical physics and biophysics, and illustrates that despite a substantial body of experimental effort, there has not yet been any study that consistently established a connection between an enzyme's conformational dynamics and a significant increase in the catalytic contribution of the chemical step. We also make the point that the dynamical proposal is not a semantic issue but a well-defined scientific hypothesis with well-defined conclusions.
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Affiliation(s)
- Arieh Warshel
- Department of Chemistry, University of Southern California, SGM 418, 3620 McClintock Avenue, Los Angeles, California 90089, USA
| | - Ram Prasad Bora
- Department of Chemistry, University of Southern California, SGM 418, 3620 McClintock Avenue, Los Angeles, California 90089, USA
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16
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Ozgur B, Ozdemir ES, Gursoy A, Keskin O. Relation between Protein Intrinsic Normal Mode Weights and Pre-Existing Conformer Populations. J Phys Chem B 2017; 121:3686-3700. [DOI: 10.1021/acs.jpcb.6b10401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Beytullah Ozgur
- Center for Computational Biology and Bioinformatics, ‡Chemical and Biological
Engineering, and §Computer Engineering,
College of Engineering, Koc University, 34450 Istanbul, Turkey
| | - E. Sila Ozdemir
- Center for Computational Biology and Bioinformatics, ‡Chemical and Biological
Engineering, and §Computer Engineering,
College of Engineering, Koc University, 34450 Istanbul, Turkey
| | - Attila Gursoy
- Center for Computational Biology and Bioinformatics, ‡Chemical and Biological
Engineering, and §Computer Engineering,
College of Engineering, Koc University, 34450 Istanbul, Turkey
| | - Ozlem Keskin
- Center for Computational Biology and Bioinformatics, ‡Chemical and Biological
Engineering, and §Computer Engineering,
College of Engineering, Koc University, 34450 Istanbul, Turkey
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17
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Holliday MJ, Camilloni C, Armstrong GS, Vendruscolo M, Eisenmesser EZ. Networks of Dynamic Allostery Regulate Enzyme Function. Structure 2017; 25:276-286. [PMID: 28089447 DOI: 10.1016/j.str.2016.12.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/28/2016] [Accepted: 12/12/2016] [Indexed: 11/16/2022]
Abstract
Many protein systems rely on coupled dynamic networks to allosterically regulate function. However, the broad conformational space sampled by non-coherently dynamic systems has precluded detailed analysis of their communication mechanisms. Here, we have developed a methodology that combines the high sensitivity afforded by nuclear magnetic resonance relaxation techniques and single-site multiple mutations, termed RASSMM, to identify two allosterically coupled dynamic networks within the non-coherently dynamic enzyme cyclophilin A. Using this methodology, we discovered two key hotspot residues, Val6 and Val29, that communicate through these networks, the mutation of which altered active-site dynamics, modulating enzymatic turnover of multiple substrates. Finally, we utilized molecular dynamics simulations to identify the mechanism by which one of these hotspots is coupled to the larger dynamic networks. These studies confirm a link between enzyme dynamics and the catalytic cycle of cyclophilin A and demonstrate how dynamic allostery may be engineered to tune enzyme function.
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Affiliation(s)
- Michael Joseph Holliday
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, 12801 East 17th Avenue, MS 8101, Aurora, CO 80045, USA
| | - Carlo Camilloni
- Department of Chemistry, Institute for Advanced Study, Technische Universität München, 85748 Garching, Germany
| | | | | | - Elan Zohar Eisenmesser
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, 12801 East 17th Avenue, MS 8101, Aurora, CO 80045, USA.
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18
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Abstract
It is well-established that dynamics are central to protein function; their importance is implicitly acknowledged in the principles of the Monod, Wyman and Changeux model of binding cooperativity, which was originally proposed in 1965. Nowadays the concept of protein dynamics is formulated in terms of the energy landscape theory, which can be used to understand protein folding and conformational changes in proteins. Because protein dynamics are so important, a key to understanding protein function at the molecular level is to design experiments that allow their quantitative analysis. Nuclear magnetic resonance (NMR) spectroscopy is uniquely suited for this purpose because major advances in theory, hardware, and experimental methods have made it possible to characterize protein dynamics at an unprecedented level of detail. Unique features of NMR include the ability to quantify dynamics (i) under equilibrium conditions without external perturbations, (ii) using many probes simultaneously, and (iii) over large time intervals. Here we review NMR techniques for quantifying protein dynamics on fast (ps-ns), slow (μs-ms), and very slow (s-min) time scales. These techniques are discussed with reference to some major discoveries in protein science that have been made possible by NMR spectroscopy.
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19
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Holliday MJ, Armstrong GS, Eisenmesser EZ. Determination of the Full Catalytic Cycle among Multiple Cyclophilin Family Members and Limitations on the Application of CPMG-RD in Reversible Catalytic Systems. Biochemistry 2015; 54:5815-27. [PMID: 26335054 DOI: 10.1021/acs.biochem.5b00746] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cyclophilins catalyze cis ↔ trans isomerization of peptidyl-prolyl bonds, influencing protein folding along with a breadth of other biological functions such as signal transduction. Here, we have determined the microscopic rate constants defining the full enzymatic cycle for three human cyclophilins and a more distantly related thermophilic bacterial cyclophilin when catalyzing interconversion of a biologically representative peptide substrate. The cyclophilins studied here exhibit variability in on-enzyme interconversion as well as an up to 2-fold range in rates of substrate binding and release. However, among the human cyclophilins, the microscopic rate constants appear to have been tuned to maintain remarkably similar isomerization rates without a concurrent conservation of apparent binding affinities. While the structures and active site compositions of the human cyclophilins studied here are highly conserved, we find that the enzymes exhibit significant variability in microsecond to millisecond time scale mobility, suggesting a role for the inherent conformational fluctuations that exist within the cyclophilin family as being functionally relevant in regulating substrate interactions. We have additionally modeled the relaxation dispersion profile given by the commonly employed Carr-Purcell-Meiboom-Gill relaxation dispersion (CPMG-RD) experiment when applied to a reversible enzymatic system such as cyclophilin isomerization and identified a significant limitation in the applicability of this approach for monitoring on-enzyme turnover. Specifically, we show both computationally and experimentally that the CPMG-RD experiment is sensitive to noncatalyzed substrate binding and release in reversible systems even at saturating substrate concentrations unless the on-enzyme interconversion rate is much faster than the substrate release rate.
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Affiliation(s)
- Michael J Holliday
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver , 12801 East 17th Avenue, Aurora, Colorado 80045, United States
| | - Geoffrey S Armstrong
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Elan Z Eisenmesser
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver , 12801 East 17th Avenue, Aurora, Colorado 80045, United States
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20
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Holliday MJ, Camilloni C, Armstrong GS, Isern NG, Zhang F, Vendruscolo M, Eisenmesser EZ. Structure and Dynamics of GeoCyp: A Thermophilic Cyclophilin with a Novel Substrate Binding Mechanism That Functions Efficiently at Low Temperatures. Biochemistry 2015; 54:3207-17. [PMID: 25923019 DOI: 10.1021/acs.biochem.5b00263] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thermophilic proteins have found extensive use in research and industrial applications because of their high stability and functionality at elevated temperatures while simultaneously providing valuable insight into our understanding of protein folding, stability, dynamics, and function. Cyclophilins, constituting a ubiquitously expressed family of peptidyl-prolyl isomerases with a range of biological functions and disease associations, have been utilized both for conferring stress tolerances and in exploring the link between conformational dynamics and enzymatic function. To date, however, no active thermophilic cyclophilin has been fully biophysically characterized. Here, we determine the structure of a thermophilic cyclophilin (GeoCyp) from Geobacillus kaustophilus, characterize its dynamic motions over several time scales using an array of methodologies that include chemical shift-based methods and relaxation experiments over a range of temperatures, and measure catalytic activity over a range of temperatures to compare its structure, dynamics, and function to those of a mesophilic counterpart, human cyclophilin A (CypA). Unlike those of most thermophile/mesophile pairs, GeoCyp catalysis is not substantially impaired at low temperatures as compared to that of CypA, retaining ~70% of the activity of its mesophilic counterpart. Examination of substrate-bound ensembles reveals a mechanism by which the two cyclophilins may have adapted to their environments through altering dynamic loop motions and a critical residue that acts as a clamp to regulate substrate binding differentially in CypA and GeoCyp. Fast time scale (pico- to nanosecond) dynamics are largely conserved between the two proteins, in accordance with the high degree of structural similarity, although differences do exist in their temperature dependencies. Slower (microsecond) time scale motions are likewise localized to similar regions in the two proteins with some variability in their magnitudes yet do not exhibit significant temperature dependencies in either enzyme.
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Affiliation(s)
- Michael J Holliday
- †Department of Biochemistry and Molecular Genetics, University of Colorado Denver, 12801 East 17th Avenue, Aurora, Colorado 80045, United States
| | - Carlo Camilloni
- ‡Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Geoffrey S Armstrong
- §Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Nancy G Isern
- ∥W. R. Wiley Environmental Molecular Sciences Laboratory, High Field NMR Facility, Richland, Washington 99354, United States
| | - Fengli Zhang
- ⊥National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | | | - Elan Z Eisenmesser
- †Department of Biochemistry and Molecular Genetics, University of Colorado Denver, 12801 East 17th Avenue, Aurora, Colorado 80045, United States
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21
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Abstract
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Biological activities of enzymes, including
regulation or coordination of mechanistic stages preceding or following
the chemical step, may depend upon kinetic or equilibrium changes
in protein conformations. Exchange of more open or flexible conformational
states with more closed or constrained states can influence inhibition,
allosteric regulation, substrate recognition, formation of the Michaelis
complex, side reactions, and product release. NMR spectroscopy has
long been applied to the study of conformational dynamic processes
in enzymes because these phenomena can be characterized over multiple
time scales with atomic site resolution. Laboratory-frame spin-relaxation
measurements, sensitive to reorientational motions on picosecond–nanosecond
time scales, and rotating-frame relaxation-dispersion measurements,
sensitive to chemical exchange processes on microsecond–millisecond
time scales, provide information on both conformational distributions
and kinetics. This Account reviews NMR spin relaxation studies of
the enzymes ribonuclease HI from mesophilic (Escherichia coli) and thermophilic (Thermus thermophilus) bacteria, E. coli AlkB, and Saccharomyces cerevisiae triosephosphate isomerase to illustrate the contributions of conformational
flexibility and dynamics to diverse steps in enzyme mechanism. Spin relaxation measurements and molecular dynamics (MD) simulations
of the bacterial ribonuclease H enzymes show that the handle region,
one of three loop regions that interact with substrates, interconverts
between two conformations. Comparison of these conformations with
the structure of the complex between Homo sapiens ribonuclease H and a DNA:RNA substrate suggests that the more closed
state is inhibitory to binding. The large population of the closed
conformation in T. thermophilus ribonuclease H contributes
to the increased Michaelis constant compared with the E. coli enzyme. NMR spin relaxation and fluorescence spectroscopy have characterized
a conformational transition in AlkB between an open state, in which
the side chains of methionine residues in the active site are disordered,
and a closed state, in which these residues are ordered. The open
state is highly populated in the AlkB/Zn(II) complex, and the closed
state is highly populated in the AlkB/Zn(II)/2OG/substrate complex,
in which 2OG is the 2-oxoglutarate cosubstrate and the substrate is
a methylated DNA oligonucleotide. The equilibrium is shifted to approximately
equal populations of the two conformations in the AlkB/Zn(II)/2OG
complex. The conformational shift induced by 2OG ensures that 2OG
binds to AlkB/Zn(II) prior to the substrate. In addition, the opening
rate of the closed conformation limits premature release of substrate,
preventing generation of toxic side products by reaction with water.
Closure of active site loop 6 in triosephosphate isomerase is critical
for forming the Michaelis complex, but reopening of the loop after
the reaction is (partially) rate limiting. NMR spin relaxation and
MD simulations of triosephosphate isomerase in complex with glycerol
3-phosphate demonstrate that closure of loop 6 is a highly correlated
rigid-body motion. The MD simulations also indicate that motions of
Gly173 in the most flexible region of loop 6 contribute to opening
of the active site loop for product release. Considered together,
these three enzyme systems illustrate the power of NMR spin relaxation
investigations in providing global insights into the role of conformational
dynamic processes in the mechanisms of enzymes from initial activation
to final product release.
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Affiliation(s)
- Arthur G. Palmer
- Department of Biochemistry and
Molecular Biophysics, Columbia University, 701 West 168th Street, New York, New York 10032, United States
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Peter E, Dick B, Stambolic I, Baeurle SA. Exploring the multiscale signaling behavior of phototropin1 from Chlamydomonas reinhardtii using a full-residue space kinetic Monte Carlo molecular dynamics technique. Proteins 2014; 82:2018-40. [PMID: 24623633 DOI: 10.1002/prot.24556] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 02/19/2014] [Accepted: 03/10/2014] [Indexed: 12/21/2022]
Abstract
Devising analysis tools for elucidating the regulatory mechanism of complex enzymes has been a challenging task for many decades. It generally requires the determination of the structural-dynamical information of protein solvent systems far from equilibrium over multiple length and time scales, which is still difficult both theoretically and experimentally. To cope with the problem, we introduce a full-residue space multiscale simulation method based on a combination of the kinetic Monte Carlo and molecular dynamics techniques, in which the rates of the rate-determining processes are evaluated from a biomolecular forcefield on the fly during the simulation run by taking into account the full space of residues. To demonstrate its reliability and efficiency, we explore the light-induced functional behavior of the full-length phototropin1 from Chlamydomonas reinhardtii (Cr-phot1) and its various subdomains. Our results demonstrate that in the dark state the light oxygen voltage-2-Jα (LOV2-Jα) photoswitch inhibits the enzymatic activity of the kinase, whereas the LOV1-Jα photoswitch controls the dimerization with the LOV2 domain. This leads to the repulsion of the LOV1-LOV2 linker out of the interface region between both LOV domains, which results in a positively charged surface suitable for cell-membrane interaction. By contrast, in the light state, we observe that the distance between both LOV domains is increased and the LOV1-LOV2 linker forms a helix-turn-helix (HTH) motif, which enables gene control through nucleotide binding. Finally, we find that the kinase is activated through the disruption of the Jα-helix from the LOV2 domain, which is followed by a stretching of the activation loop (A-loop) and broadening of the catalytic cleft of the kinase.
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Affiliation(s)
- Emanuel Peter
- Department of Chemistry and Pharmacy, Institute of Physical and Theoretical Chemistry, University of Regensburg, D-93040, Regensburg, Germany
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23
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Vögeli B, Orts J, Strotz D, Chi C, Minges M, Wälti MA, Güntert P, Riek R. Towards a true protein movie: a perspective on the potential impact of the ensemble-based structure determination using exact NOEs. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 241:53-59. [PMID: 24656080 DOI: 10.1016/j.jmr.2013.11.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 06/03/2023]
Abstract
Confined by the Boltzmann distribution of the energies of the states, a multitude of structural states are inherent to biomolecules. For a detailed understanding of a protein's function, its entire structural landscape at atomic resolution and insight into the interconversion between all the structural states (i.e. dynamics) are required. Whereas dedicated trickery with NMR relaxation provides aspects of local dynamics, and 3D structure determination by NMR is well established, only recently have several attempts been made to formulate a more comprehensive description of the dynamics and the structural landscape of a protein. Here, a perspective is given on the use of exact NOEs (eNOEs) for the elucidation of structural ensembles of a protein describing the covered conformational space.
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Affiliation(s)
- Beat Vögeli
- Laboratory of Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland.
| | - Julien Orts
- Laboratory of Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - Dean Strotz
- Laboratory of Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - Celestine Chi
- Laboratory of Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - Martina Minges
- Laboratory of Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - Marielle Aulikki Wälti
- Laboratory of Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - Peter Güntert
- Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance, and Frankfurt Institute for Advanced Studies, J.W. Goethe-Universität, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany; Graduate School of Science, Tokyo Metropolitan University, Hachioji, 192-0397 Tokyo, Japan
| | - Roland Riek
- Laboratory of Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland.
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24
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Lee SY, Pullen L, Virgil DJ, Castañeda CA, Abeykoon D, Bolon DNA, Fushman D. Alanine scan of core positions in ubiquitin reveals links between dynamics, stability, and function. J Mol Biol 2013; 426:1377-89. [PMID: 24361330 DOI: 10.1016/j.jmb.2013.10.042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/25/2013] [Accepted: 10/26/2013] [Indexed: 11/17/2022]
Abstract
Mutations at solvent-inaccessible core positions in proteins can impact function through many biophysical mechanisms including alterations to thermodynamic stability and protein dynamics. As these properties of proteins are difficult to investigate, the impacts of core mutations on protein function are poorly understood for most systems. Here, we determined the effects of alanine mutations at all 15 core positions in ubiquitin on function in yeast. The majority (13 of 15) of alanine substitutions supported yeast growth as the sole ubiquitin. Both the two null mutants (I30A and L43A) were less stable to temperature-induced unfolding in vitro than wild type (WT) but were well folded at physiological temperatures. Heteronuclear NMR studies indicated that the L43A mutation reduces temperature stability while retaining a ground-state structure similar to WT. This structure enables L43A to bind to common ubiquitin receptors in vitro. Many of the core alanine ubiquitin mutants, including one of the null variants (I30A), exhibited an increased accumulation of high-molecular-weight species, suggesting that these mutants caused a defect in the processing of ubiquitin-substrate conjugates. In contrast, L43A exhibited a unique accumulation pattern with reduced levels of high-molecular-weight species and undetectable levels of free ubiquitin. When conjugation to other proteins was blocked, L43A ubiquitin accumulated as free ubiquitin in yeast. Based on these findings, we speculate that ubiquitin's stability to unfolding may be required for efficient recycling during proteasome-mediated substrate degradation.
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Affiliation(s)
- Shirley Y Lee
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742, USA
| | - Lester Pullen
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Daniel J Virgil
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Carlos A Castañeda
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742, USA
| | - Dulith Abeykoon
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742, USA
| | - Daniel N A Bolon
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - David Fushman
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742, USA.
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25
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Schrank TP, Wrabl JO, Hilser VJ. Conformational heterogeneity within the LID domain mediates substrate binding to Escherichia coli adenylate kinase: function follows fluctuations. Top Curr Chem (Cham) 2013; 337:95-121. [PMID: 23543318 DOI: 10.1007/128_2012_410] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Proteins exist as dynamic ensembles of molecules, implying that protein amino acid sequences evolved to code for both the ground state structure as well as the entire energy landscape of excited states. Accumulating theoretical and experimental evidence suggests that enzymes use such conformational fluctuations to facilitate allosteric processes important for substrate binding and possibly catalysis. This phenomenon can be clearly demonstrated in Escherichia coli adenylate kinase, where experimentally observed local unfolding of the LID subdomain, as opposed to a more commonly postulated rigid-body opening motion, is related to substrate binding. Because "entropy promoting" glycine mutations designed to increase specifically the local unfolding of the LID domain also affect substrate binding, changes in the excited energy landscape effectively tune the function of this enzyme without changing the ground state structure or the catalytic site. Thus, additional thermodynamic information, above and beyond the single folded structure of an enzyme-substrate complex, is likely required for a full and quantitative understanding of how enzymes work.
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Affiliation(s)
- Travis P Schrank
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, 301 University Boulevard, Galveston, TX, 77555-1068, USA,
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26
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Heidarsson PO, Naqvi MM, Sonar P, Valpapuram I, Cecconi C. Conformational Dynamics of Single Protein Molecules Studied by Direct Mechanical Manipulation. DYNAMICS OF PROTEINS AND NUCLEIC ACIDS 2013; 92:93-133. [DOI: 10.1016/b978-0-12-411636-8.00003-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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27
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Liuni P, Jeganathan A, Wilson DJ. Conformer selection and intensified dynamics during catalytic turnover in chymotrypsin. Angew Chem Int Ed Engl 2012; 51:9666-9. [PMID: 22936643 DOI: 10.1002/anie.201204903] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/31/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Peter Liuni
- Chemistry, York University, 4700 Keele St., Toronto, ON, Canada
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28
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Liuni P, Jeganathan A, Wilson DJ. Conformer Selection and Intensified Dynamics During Catalytic Turnover in Chymotrypsin. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201204903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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29
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Ladani ST, Hamelberg D. Entropic and Surprisingly Small Intramolecular Polarization Effects in the Mechanism of Cyclophilin A. J Phys Chem B 2012; 116:10771-8. [DOI: 10.1021/jp305917c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Safieh Tork Ladani
- Department of Chemistry and Center
for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302-4098, United States
| | - Donald Hamelberg
- Department of Chemistry and Center
for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302-4098, United States
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30
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Traaseth NJ, Chao FA, Masterson LR, Mangia S, Garwood M, Michaeli S, Seelig B, Veglia G. Heteronuclear Adiabatic Relaxation Dispersion (HARD) for quantitative analysis of conformational dynamics in proteins. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 219:75-82. [PMID: 22621977 PMCID: PMC3568944 DOI: 10.1016/j.jmr.2012.03.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 03/22/2012] [Accepted: 03/29/2012] [Indexed: 05/09/2023]
Abstract
NMR relaxation methods probe biomolecular motions over a wide range of timescales. In particular, the rotating frame spin-lock R(1ρ) and Carr-Purcell-Meiboom-Gill (CPMG) R(2) experiments are commonly used to characterize μs to ms dynamics, which play a critical role in enzyme folding and catalysis. In an effort to complement these approaches, we introduced the Heteronuclear Adiabatic Relaxation Dispersion (HARD) method, where dispersion in rotating frame relaxation rate constants (longitudinal R(1ρ) and transverse R(2ρ)) is created by modulating the shape and duration of adiabatic full passage (AFP) pulses. Previously, we showed the ability of the HARD method to detect chemical exchange dynamics in the fast exchange regime (k(ex)∼10(4)-10(5) s(-1)). In this article, we show the sensitivity of the HARD method to slower exchange processes by measuring R(1ρ) and R(2ρ) relaxation rates for two soluble proteins (ubiquitin and 10C RNA ligase). One advantage of the HARD method is its nominal dependence on the applied radio frequency field, which can be leveraged to modulate the dispersion in the relaxation rate constants. In addition, we also include product operator simulations to define the dynamic range of adiabatic R(1ρ) and R(2ρ) that is valid under all exchange regimes. We conclude from both experimental observations and simulations that this method is complementary to CPMG-based and rotating frame spin-lock R(1ρ) experiments to probe conformational exchange dynamics for biomolecules. Finally, this approach is germane to several NMR-active nuclei, where relaxation rates are frequency-offset independent.
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Affiliation(s)
- Nathaniel J. Traaseth
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
- Department of Chemistry, New York University, New York, NY 10003, United States
| | - Fa-An Chao
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Larry R. Masterson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Silvia Mangia
- Department of Radiology (Center for Magnetic Resonance Research), University of Minnesota, Minneapolis, MN 55455, United States
| | - Michael Garwood
- Department of Radiology (Center for Magnetic Resonance Research), University of Minnesota, Minneapolis, MN 55455, United States
| | - Shalom Michaeli
- Department of Radiology (Center for Magnetic Resonance Research), University of Minnesota, Minneapolis, MN 55455, United States
| | - Burckhard Seelig
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
- BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, United States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
- Corresponding author. Address: 6-155 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, United States. Fax: +1 612 625 2163. (G. Veglia)
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31
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Potoyan DA, Zhuravlev PI, Papoian GA. Computing Free Energy of a Large-Scale Allosteric Transition in Adenylate Kinase Using All Atom Explicit Solvent Simulations. J Phys Chem B 2012; 116:1709-15. [DOI: 10.1021/jp209980b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Davit A. Potoyan
- Institute
for Physical Science and Technology, ‡Chemical Physics Program, and §Department of Chemistry
and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Pavel I. Zhuravlev
- Institute
for Physical Science and Technology, ‡Chemical Physics Program, and §Department of Chemistry
and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Garegin A. Papoian
- Institute
for Physical Science and Technology, ‡Chemical Physics Program, and §Department of Chemistry
and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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32
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Veljkovic N, Glisic S, Perovic V, Veljkovic V. The role of long-range intermolecular interactions in discovery of new drugs. Expert Opin Drug Discov 2011; 6:1263-70. [PMID: 22647065 DOI: 10.1517/17460441.2012.638280] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Long-range intermolecular interactions (interactions at distances between 100 and 1000 Å) play an important role in the interaction between drugs and therapeutic targets, and design techniques based on this concept could significantly improve and accelerate new drug discovery. Understanding these long-range intermolecular interactions will also help further our understanding of the molecular mechanisms and the underlying basic biological processes. AREAS COVERED This article looks at the physical bases of long-range intermolecular interactions in biological systems with a brief review of the literature data to support this concept. The article also gives some examples of techniques used in drug discovery that were based on the long-range intermolecular interaction concept. EXPERT OPINION The electron-ion interaction potential (EIIP) and average quasivalence number (AQVN) concepts shed new light on the role of long-range intermolecular interactions in biological systems. Further research of physicochemical mechanisms underlying long-range interactions between biological molecules is necessary for a better understanding of the basic biological processes. The addition of the computer-aided design techniques based on the EIIP/AQVN concept to the research and development will lead not only to a significant reduction in cost but also to an acceleration in the development of new drugs.
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Affiliation(s)
- Nevena Veljkovic
- University of Belgrade, Institute of Nuclear Sciences Vinca , Center for Multidisciplinary Research, P.O.Box 522, 11001 Belgrade , Serbia +381 11 2453 686 ; +381 11 3440 100 ;
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33
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Li P, Martins IRS, Rosen MK. The feasibility of parameterizing four-state equilibria using relaxation dispersion measurements. JOURNAL OF BIOMOLECULAR NMR 2011; 51:57-70. [PMID: 21947915 PMCID: PMC3229927 DOI: 10.1007/s10858-011-9541-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 07/07/2011] [Indexed: 05/03/2023]
Abstract
Coupled equilibria play important roles in controlling information flow in biochemical systems, including allosteric molecules and multidomain proteins. In the simplest case, two equilibria are coupled to produce four interconverting states. In this study, we assessed the feasibility of determining the degree of coupling between two equilibria in a four-state system via relaxation dispersion measurements. A major bottleneck in this effort is the lack of efficient approaches to data analysis. To this end, we designed a strategy to efficiently evaluate the smoothness of the target function surface (TFS). Using this approach, we found that the TFS is very rough when fitting benchmark CPMG data to all adjustable variables of the four-state equilibria. After constraining a portion of the adjustable variables, which can often be achieved through independent biochemical manipulation of the system, the smoothness of TFS improves dramatically, although it is still insufficient to pinpoint the solution. The four-state equilibria can be finally solved with further incorporation of independent chemical shift information that is readily available. We also used Monte Carlo simulations to evaluate how well each adjustable parameter can be determined in a large kinetic and thermodynamic parameter space and how much improvement can be achieved in defining the parameters through additional measurements. The results show that in favorable conditions the combination of relaxation dispersion and biochemical manipulation allow the four-state equilibrium to be parameterized, and thus coupling strength between two processes to be determined.
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Affiliation(s)
- Pilong Li
- Department of Biochemistry and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA.
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34
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Clore GM. Exploring sparsely populated states of macromolecules by diamagnetic and paramagnetic NMR relaxation. Protein Sci 2011; 20:229-46. [PMID: 21280116 DOI: 10.1002/pro.576] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sparsely populated states of macromolecules, characterized by short lifetimes and high free-energies relative to the predominant ground state, often play a key role in many biological, chemical, and biophysical processes. In this review, we briefly summarize various new developments in NMR spectroscopy that permit these heretofore invisible, sparsely populated states to be detected, characterized, and in some instances visualized. Relaxation dispersion spectroscopy yields detailed kinetic information on processes involving species characterized by distinct chemical shifts with lifetimes in the ∼50 μs-10 ms range and populations as low as 0.5%. In the fast exchange regime (time scale less than ∼250-500 μs), the footprint of sparsely populated states can be observed on paramagnetic relaxation enhancement profiles measured on the resonances of the major species, thereby yielding structural information that is directly related to paramagnetic center-nuclei distances from which it is possible, under suitable circumstances, to compute a structure or ensemble of structures for the minor species. Finally, differential transverse relaxation measurements can be used to detect lifetime broadening effects that directly reflect the unidirectional rates for the conversion of NMR-visible into high-molecular weight NMR-invisible species. Examples of these various approaches are presented.
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Affiliation(s)
- G Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA.
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35
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Hansen DF, Kay LE. Determining Valine Side-Chain Rotamer Conformations in Proteins from Methyl 13C Chemical Shifts: Application to the 360 kDa Half-Proteasome. J Am Chem Soc 2011; 133:8272-81. [DOI: 10.1021/ja2014532] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- D. Flemming Hansen
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Lewis E. Kay
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, Ontario M5S 1A8, Canada
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36
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Verdegem D, Badillo A, Wieruszeski JM, Landrieu I, Leroy A, Bartenschlager R, Penin F, Lippens G, Hanoulle X. Domain 3 of NS5A protein from the hepatitis C virus has intrinsic alpha-helical propensity and is a substrate of cyclophilin A. J Biol Chem 2011; 286:20441-54. [PMID: 21489988 DOI: 10.1074/jbc.m110.182436] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nonstructural protein 5A (NS5A) is essential for hepatitis C virus (HCV) replication and constitutes an attractive target for antiviral drug development. Although structural data for its in-plane membrane anchor and domain D1 are available, the structure of domains 2 (D2) and 3 (D3) remain poorly defined. We report here a comparative molecular characterization of the NS5A-D3 domains of the HCV JFH-1 (genotype 2a) and Con1 (genotype 1b) strains. Combining gel filtration, CD, and NMR spectroscopy analyses, we show that NS5A-D3 is natively unfolded. However, NS5A-D3 domains from both JFH-1 and Con1 strains exhibit a propensity to partially fold into an α-helix. NMR analysis identifies two putative α-helices, for which a molecular model could be obtained. The amphipathic nature of the first helix and its conservation in all genotypes suggest that it might correspond to a molecular recognition element and, as such, promote the interaction with relevant biological partner(s). Because mutations conferring resistance to cyclophilin inhibitors have been mapped into NS5A-D3, we also investigated the functional interaction between NS5A-D3 and cyclophilin A (CypA). CypA indeed interacts with NS5A-D3, and this interaction is completely abolished by cyclosporin A. NMR heteronuclear exchange experiments demonstrate that CypA has in vitro peptidyl-prolyl cis/trans-isomerase activity toward some, but not all, of the peptidyl-prolyl bonds in NS5A-D3. These studies lead to novel insights into the structural features of NS5A-D3 and its relationships with CypA.
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Jeon J, Nam HJ, Choi YS, Yang JS, Hwang J, Kim S. Molecular evolution of protein conformational changes revealed by a network of evolutionarily coupled residues. Mol Biol Evol 2011; 28:2675-85. [PMID: 21470969 DOI: 10.1093/molbev/msr094] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
An improved understanding of protein conformational changes has broad implications for elucidating the mechanisms of various biological processes and for the design of protein engineering experiments. Understanding rearrangements of residue interactions is a key component in the challenge of describing structural transitions. Evolutionary properties of protein sequences and structures are extensively studied; however, evolution of protein motions, especially with respect to interaction rearrangements, has yet to be explored. Here, we investigated the relationship between sequence evolution and protein conformational changes and discovered that structural transitions are encoded in amino acid sequences as coevolving residue pairs. Furthermore, we found that highly coevolving residues are clustered in the flexible regions of proteins and facilitate structural transitions by forming and disrupting their interactions cooperatively. Our results provide insight into the evolution of protein conformational changes and help to identify residues important for structural transitions.
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Affiliation(s)
- Jouhyun Jeon
- Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, Korea
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38
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Jensen KS, Winther JR, Teilum K. Millisecond dynamics in glutaredoxin during catalytic turnover is dependent on substrate binding and absent in the resting states. J Am Chem Soc 2011; 133:3034-42. [PMID: 21323311 DOI: 10.1021/ja1096539] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Conformational dynamics is important for enzyme function. Which motions of enzymes determine catalytic efficiency and whether the same motions are important for all enzymes, however, are not well understood. Here we address conformational dynamics in glutaredoxin during catalytic turnover with a combination of NMR magnetization transfer, R(2) relaxation dispersion, and ligand titration experiments. Glutaredoxins catalyze a glutathione exchange reaction, forming a stable glutathinoylated enzyme intermediate. The equilibrium between the reduced state and the glutathionylated state was biochemically tuned to exchange on the millisecond time scale. The conformational changes of the protein backbone during catalysis were followed by (15)N nuclear spin relaxation dispersion experiments. A conformational transition that is well described by a two-state process with an exchange rate corresponding to the glutathione exchange rate was observed for 23 residues. Binding of reduced glutathione resulted in competitive inhibition of the reduced enzyme having kinetics similar to that of the reaction. This observation couples the motions observed during catalysis directly to substrate binding. Backbone motions on the time scale of catalytic turnover were not observed for the enzyme in the resting states, implying that alternative conformers do not accumulate to significant concentrations. These results infer that the turnover rate in glutaredoxin is governed by formation of a productive enzyme-substrate encounter complex, and that catalysis proceeds by an induced fit mechanism rather than by conformer selection driven by intrinsic conformational dynamics.
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Affiliation(s)
- Kristine Steen Jensen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark
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39
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Jiang J, Mukamel S. Two-dimensional near-ultraviolet spectroscopy of aromatic residues in amyloid fibrils: a first principles study. Phys Chem Chem Phys 2011; 13:2394-400. [PMID: 21132201 PMCID: PMC3141107 DOI: 10.1039/c0cp02047h] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a first principles study of two dimensional electronic spectroscopy of aromatic side chain transitions in the 32-residue β-amyloid (Aβ(9-40)) fibrils in the near ultraviolet (250-300 nm). An efficient exciton Hamiltonian with electrostatic fluctuations (EHEF) algorithm is used to compute the electronic excitations in the presence of environmental fluctuations. The through-space inter- and intra-molecular interactions are calculated with high level quantum mechanics (QM) approaches, and interfaced with molecular mechanics (MM) simulations. Distinct two dimensional near ultraviolet (2DNUV) spectroscopic signatures are identified for different aromatic transitions, and the couplings between them. 2DNUV signals associated with the transition couplings are shown to be very sensitive to the change of residue-residue interactions induced by residue mutations. Our simulations suggest that 2DNUV spectra could provide a useful local probe for the structure and kinetics of fibrils.
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Affiliation(s)
- Jun Jiang
- Chemistry Department, University of California Irvine, USA
| | - Shaul Mukamel
- Chemistry Department, University of California Irvine, USA
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40
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Peptide Bond cis/trans Isomerases: A Biocatalysis Perspective of Conformational Dynamics in Proteins. Top Curr Chem (Cham) 2011; 328:35-67. [DOI: 10.1007/128_2011_151] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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41
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Wang X, Kleerekoper QK, Xiong LW, Putkey JA. Intrinsically disordered PEP-19 confers unique dynamic properties to apo and calcium calmodulin. Biochemistry 2010; 49:10287-97. [PMID: 20973509 DOI: 10.1021/bi100500m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
PEP-19 (Purkinje cell protein 4) is an intrinsically disordered protein with an IQ calmodulin (CaM) binding motif. Expression of PEP-19 was recently shown to protect cells from apoptosis and cell death due to Ca(2+) overload. Our initial studies showed that PEP-19 causes novel and dramatic increases in the rates of association of Ca(2+) with and dissociation of Ca(2+) from the C-domain of CaM. The goal of this work was to study interactions between the C-domain of CaM (C-CaM) and PEP-19 by solution nuclear magnetic resonance (NMR) to identify mechanisms by which PEP-19 regulates binding of Ca(2+) to CaM. Our results show that PEP-19 causes a greater structural change in apo C-CaM than in Ca(2+)-C-CaM, and that the first Ca(2+) binds preferentially to site IV in the presence of PEP-19 with exchange characteristics that are consistent with a decrease in Ca(2+) binding cooperativity. Relatively weak binding of PEP-19 has distinct effects on chemical and conformational exchange on the microsecond to millisecond time scale. In apo C-CaM, PEP-19 binding causes a redistribution of residues that experience conformational exchange, leading to an increase in the number of residues around Ca(2+) binding site IV that undergo conformational exchange on the microsecond to millisecond time scale. This appears to be caused by an allosteric effect because these residues are not localized to the PEP-19 binding site. In contrast, PEP-19 increases the number of residues that exhibit conformational exchange in Ca(2+)-C-CaM. These residues are primarily localized to the PEP-19 binding site but also include Asp93 in site III. These results provide working models for the role of protein dynamics in the regulation of binding of Ca(2+) to CaM by PEP-19.
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Affiliation(s)
- Xu Wang
- Department of Biochemistry and Molecular Biology and Structural Biology Center, University of Texas-Houston Medical School, 6431 Fannin Street, Houston, TX 77030, USA
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42
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Kleckner IR, Foster MP. An introduction to NMR-based approaches for measuring protein dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:942-68. [PMID: 21059410 DOI: 10.1016/j.bbapap.2010.10.012] [Citation(s) in RCA: 346] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 10/27/2010] [Accepted: 10/29/2010] [Indexed: 01/15/2023]
Abstract
Proteins are inherently flexible at ambient temperature. At equilibrium, they are characterized by a set of conformations that undergo continuous exchange within a hierarchy of spatial and temporal scales ranging from nanometers to micrometers and femtoseconds to hours. Dynamic properties of proteins are essential for describing the structural bases of their biological functions including catalysis, binding, regulation and cellular structure. Nuclear magnetic resonance (NMR) spectroscopy represents a powerful technique for measuring these essential features of proteins. Here we provide an introduction to NMR-based approaches for studying protein dynamics, highlighting eight distinct methods with recent examples, contextualized within a common experimental and analytical framework. The selected methods are (1) Real-time NMR, (2) Exchange spectroscopy, (3) Lineshape analysis, (4) CPMG relaxation dispersion, (5) Rotating frame relaxation dispersion, (6) Nuclear spin relaxation, (7) Residual dipolar coupling, (8) Paramagnetic relaxation enhancement. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
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Affiliation(s)
- Ian R Kleckner
- The Ohio State University Biophysics Program, 484 West 12th Ave Room 776, Columbus, OH 43210, USA
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43
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Protein functional landscapes, dynamics, allostery: a tortuous path towards a universal theoretical framework. Q Rev Biophys 2010; 43:295-332. [DOI: 10.1017/s0033583510000119] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
AbstractEnergy landscape theories have provided a common ground for understanding the protein folding problem, which once seemed to be overwhelmingly complicated. At the same time, the native state was found to be an ensemble of interconverting states with frustration playing a more important role compared to the folding problem. The landscape of the folded protein – the native landscape – is glassier than the folding landscape; hence, a general description analogous to the folding theories is difficult to achieve. On the other hand, the native basin phase volume is much smaller, allowing a protein to fully sample its native energy landscape on the biological timescales. Current computational resources may also be used to perform this sampling for smaller proteins, to build a ‘topographical map’ of the native landscape that can be used for subsequent analysis. Several major approaches to representing this topographical map are highlighted in this review, including the construction of kinetic networks, hierarchical trees and free energy surfaces with subsequent structural and kinetic analyses. In this review, we extensively discuss the important question of choosing proper collective coordinates characterizing functional motions. In many cases, the substates on the native energy landscape, which represent different functional states, can be used to obtain variables that are well suited for building free energy surfaces and analyzing the protein's functional dynamics. Normal mode analysis can provide such variables in cases where functional motions are dictated by the molecule's architecture. Principal component analysis is a more expensive way of inferring the essential variables from the protein's motions, one that requires a long molecular dynamics simulation. Finally, the two popular models for the allosteric switching mechanism, ‘preexisting equilibrium’ and ‘induced fit’, are interpreted within the energy landscape paradigm as extreme points of a continuum of transition mechanisms. Some experimental evidence illustrating each of these two models, as well as intermediate mechanisms, is presented and discussed.
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44
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Cogliati C, Ragona L, D'Onofrio M, Günther U, Whittaker S, Ludwig C, Tomaselli S, Assfalg M, Molinari H. Site-Specific Investigation of the Steady-State Kinetics and Dynamics of the Multistep Binding of Bile Acid Molecules to a Lipid Carrier Protein. Chemistry 2010; 16:11300-10. [DOI: 10.1002/chem.201000498] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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45
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Davis TL, Walker JR, Campagna-Slater V, Finerty PJ, Paramanathan R, Bernstein G, MacKenzie F, Tempel W, Ouyang H, Lee WH, Eisenmesser EZ, Dhe-Paganon S. Structural and biochemical characterization of the human cyclophilin family of peptidyl-prolyl isomerases. PLoS Biol 2010; 8:e1000439. [PMID: 20676357 PMCID: PMC2911226 DOI: 10.1371/journal.pbio.1000439] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 06/16/2010] [Indexed: 11/29/2022] Open
Abstract
Peptidyl-prolyl isomerases catalyze the conversion between cis and trans isomers of proline. The cyclophilin family of peptidyl-prolyl isomerases is well known for being the target of the immunosuppressive drug cyclosporin, used to combat organ transplant rejection. There is great interest in both the substrate specificity of these enzymes and the design of isoform-selective ligands for them. However, the dearth of available data for individual family members inhibits attempts to design drug specificity; additionally, in order to define physiological functions for the cyclophilins, definitive isoform characterization is required. In the current study, enzymatic activity was assayed for 15 of the 17 human cyclophilin isomerase domains, and binding to the cyclosporin scaffold was tested. In order to rationalize the observed isoform diversity, the high-resolution crystallographic structures of seven cyclophilin domains were determined. These models, combined with seven previously solved cyclophilin isoforms, provide the basis for a family-wide structure:function analysis. Detailed structural analysis of the human cyclophilin isomerase explains why cyclophilin activity against short peptides is correlated with an ability to ligate cyclosporin and why certain isoforms are not competent for either activity. In addition, we find that regions of the isomerase domain outside the proline-binding surface impart isoform specificity for both in vivo substrates and drug design. We hypothesize that there is a well-defined molecular surface corresponding to the substrate-binding S2 position that is a site of diversity in the cyclophilin family. Computational simulations of substrate binding in this region support our observations. Our data indicate that unique isoform determinants exist that may be exploited for development of selective ligands and suggest that the currently available small-molecule and peptide-based ligands for this class of enzyme are insufficient for isoform specificity.
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Affiliation(s)
- Tara L. Davis
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - John R. Walker
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | | | - Patrick J. Finerty
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Ragika Paramanathan
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Galina Bernstein
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Farrell MacKenzie
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Wolfram Tempel
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Hui Ouyang
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Wen Hwa Lee
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- University of Oxford, Headington, United Kingdom
| | - Elan Z. Eisenmesser
- Department of Biochemistry & Molecular Genetics, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Sirano Dhe-Paganon
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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46
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Jiang J, Abramavicius D, Bulheller BM, Hirst JD, Mukamel S. Ultraviolet spectroscopy of protein backbone transitions in aqueous solution: combined QM and MM simulations. J Phys Chem B 2010; 114:8270-7. [PMID: 20503991 PMCID: PMC2888931 DOI: 10.1021/jp101980a] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A generalized approach combining quantum mechanics (QM) and molecular mechanics (MM) calculations is developed to simulate the n --> pi* and pi --> pi* backbone transitions of proteins in aqueous solution. These transitions, which occur in the ultraviolet (UV) at 180-220 nm, provide a sensitive probe for secondary structures. The excitation Hamiltonian is constructed using high-level electronic structure calculations of N-methylacetamide (NMA). Its electrostatic fluctuations are modeled using a new algorithm, EHEF, which combines a molecular dynamics (MD) trajectory obtained with a MM forcefield and electronic structures of sampled MD snapshots calculated by QM. The lineshapes and excitation splittings induced by the electrostatic environment in the experimental UV linear absorption (LA) and circular dichroism (CD) spectra of several proteins in aqueous solution are reproduced by our calculations. The distinct CD features of alpha-helix and beta-sheet protein structures are observed in the simulations and can be assigned to different backbone geometries. The fine structure of the UV spectra is accurately characterized and enables us to identify signatures of secondary structures.
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Affiliation(s)
- Jun Jiang
- Chemistry Department, University of California Irvine, USA
| | | | - Benjamin M. Bulheller
- School of Chemistry, University of Nottingham, University Park Nottingham NG7 2RD UK
| | - Jonathan D. Hirst
- School of Chemistry, University of Nottingham, University Park Nottingham NG7 2RD UK
| | - Shaul Mukamel
- Chemistry Department, University of California Irvine, USA
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47
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Shen A. Allosteric regulation of protease activity by small molecules. MOLECULAR BIOSYSTEMS 2010; 6:1431-43. [PMID: 20539873 DOI: 10.1039/c003913f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Proteases regulate a plethora of biological processes. Because they irreversibly cleave peptide bonds, the activity of proteases is strictly controlled. While there are many ways to regulate protease activity, an emergent mechanism is the modulation of protease function by small molecules acting at allosteric sites. This mode of regulation holds the potential to allow for the specific and temporal control of a given biological process using small molecules. These compounds also serve as useful tools for studying protein dynamics and function. This review highlights recent advances in identifying and characterizing natural and synthetic small molecule allosteric regulators of proteases and discusses their utility in studies of protease function, drug discovery and protein engineering.
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Affiliation(s)
- Aimee Shen
- Department of Pathology, Stanford School of Medicine, Stanford, California 94305, USA.
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48
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Kamerlin SCL, Warshel A. At the dawn of the 21st century: Is dynamics the missing link for understanding enzyme catalysis? Proteins 2010; 78:1339-75. [PMID: 20099310 PMCID: PMC2841229 DOI: 10.1002/prot.22654] [Citation(s) in RCA: 356] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Enzymes play a key role in almost all biological processes, accelerating a variety of metabolic reactions as well as controlling energy transduction, the transcription, and translation of genetic information, and signaling. They possess the remarkable capacity to accelerate reactions by many orders of magnitude compared to their uncatalyzed counterparts, making feasible crucial processes that would otherwise not occur on biologically relevant timescales. Thus, there is broad interest in understanding the catalytic power of enzymes on a molecular level. Several proposals have been put forward to try to explain this phenomenon, and one that has rapidly gained momentum in recent years is the idea that enzyme dynamics somehow contributes to catalysis. This review examines the dynamical proposal in a critical way, considering basically all reasonable definitions, including (but not limited to) such proposed effects as "coupling between conformational and chemical motions," "landscape searches" and "entropy funnels." It is shown that none of these proposed effects have been experimentally demonstrated to contribute to catalysis, nor are they supported by consistent theoretical studies. On the other hand, it is clarified that careful simulation studies have excluded most (if not all) dynamical proposals. This review places significant emphasis on clarifying the role of logical definitions of different catalytic proposals, and on the need for a clear formulation in terms of the assumed potential surface and reaction coordinate. Finally, it is pointed out that electrostatic preorganization actually accounts for the observed catalytic effects of enzymes, through the corresponding changes in the activation free energies.
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Affiliation(s)
- Shina C. L. Kamerlin
- Department of Chemistry, University of Southern California, 3620 McClintock Ave., Los Angeles CA-90089, USA
| | - Arieh Warshel
- Department of Chemistry, University of Southern California, 3620 McClintock Ave., Los Angeles CA-90089, USA
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49
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Alegre-Cebollada J, Perez-Jimenez R, Kosuri P, Fernandez JM. Single-molecule force spectroscopy approach to enzyme catalysis. J Biol Chem 2010; 285:18961-6. [PMID: 20382731 DOI: 10.1074/jbc.r109.011932] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Enzyme catalysis has been traditionally studied using a diverse set of techniques such as bulk biochemistry, x-ray crystallography, and NMR. Recently, single-molecule force spectroscopy by atomic force microscopy has been used as a new tool to study the catalytic properties of an enzyme. In this approach, a mechanical force ranging up to hundreds of piconewtons is applied to the substrate of an enzymatic reaction, altering the conformational energy of the substrate-enzyme interactions during catalysis. From these measurements, the force dependence of an enzymatic reaction can be determined. The force dependence provides valuable new information about the dynamics of enzyme catalysis with sub-angstrom resolution, a feat unmatched by any other current technique. To date, single-molecule force spectroscopy has been applied to gain insight into the reduction of disulfide bonds by different enzymes of the thioredoxin family. This minireview aims to present a perspective on this new approach to study enzyme catalysis and to summarize the results that have already been obtained from it. Finally, the specific requirements that must be fulfilled to apply this new methodology to any other enzyme will be discussed.
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50
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Jordan F, Arjunan P, Kale S, Nemeria NS, Furey W. Multiple roles of mobile active center loops in the E1 component of the Escherichia coli pyruvate dehydrogenase complex - Linkage of protein dynamics to catalysis. JOURNAL OF MOLECULAR CATALYSIS. B, ENZYMATIC 2009; 61:14-22. [PMID: 20160956 PMCID: PMC2759092 DOI: 10.1016/j.molcatb.2009.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The region encompassing residues 401-413 on the E1 component of the pyruvate dehydrogenase multienzyme complex from Escherichia coli comprises a loop (the inner loop) which was not seen in the X-ray structure in the presence of thiamin diphosphate, the required cofactor for the enzyme. This loop is seen in the presence of a stable analogue of the pre-decarboxylation intermediate, the covalent adduct between the substrate analogue methyl acetylphosphonate and thiamin diphosphate, C2α-phosphonolactylthiamin diphosphate. It has been shown that the residue H407 and several other residues on this loop are required to reduce the mobility of the loop so electron density corresponding to it can be seen once the pre-decarboxylation intermediate is formed. Concomitantly, the loop encompassing residues 541-557 (the outer loop) appears to work in tandem with the inner loop and there is a hydrogen bond between the two loops ensuring their correlated motion. The inner loop was shown to: a) sequester the active center from carboligase side reactions; b) assist the interaction between the E1 and the E2 components, thereby affecting the overall reaction rate of the entire multienzyme complex; c) control substrate access to the active center. Using viscosity effects on kinetics it was shown that formation of the pre-decarboxylation intermediate is specifically affected by loop movement. A cysteine-less variant was created for the E1 component, onto which cysteines were substituted at selected loop positions. Introducing an electron spin resonance spin label and an (19)F NMR label onto these engineered cysteines, the loop mobility was examined: a) both methods suggested that in the absence of ligand, the loop exists in two conformations; b) line-shape analysis of the NMR signal at different temperatures, enabled estimation of the rate constant for loop movement, and this rate constant was found to be of the same order of magnitude as the turnover number for the enzyme under the same conditions. Furthermore, this analysis gave important insights into rate-limiting thermal loop dynamics. Overall, the results suggest that the dynamic properties correlate with catalytic events on the E1 component of the pyruvate dehydrogenase complex.
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Affiliation(s)
- Frank Jordan
- Department of Chemistry, Rutgers University, Newark, New Jersey 07102
| | - Palaniappa Arjunan
- Biocrystallography Laboratory, Veterans Affairs Medical Center, Pittsburgh, Pennsylvania 15240
| | - Sachin Kale
- Department of Chemistry, Rutgers University, Newark, New Jersey 07102
| | | | - William Furey
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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